A conventional example discloses a motorcycle loaded with a so-called AMT (Automated Manual Transmission) transmission that performs a speed change operation, that is, a clutch operation and an operation of a change mechanism by electric power in a constant-mesh transmission. In the conventional example, rotational power from the engine is inputted to a main shaft of the transmission via a change clutch, is transmitted to a countershaft (also serving as an output shaft) via a constant-mesh gear, and is transmitted to a rear wheel as a driving wheel from the output shaft, through a driving force transmitting device configured by a driving/driven sprocket and a winding chain. The change clutch is operated to be disengaged and engaged by a clutch lever (a clutch operation member) provided at a motor-driven shift spindle (refer to Patent Literature 1, for example).
The conventional change mechanism includes a master arm, a shift drum rotated by the master arm, and a shift fork that is driven by the shift drum and moves a shifter gear forming a part of a gear train of the transmission in an axial direction. Further, on a shift spindle, a power storing mechanism is provided, which includes a gearshift arm that is provided to be relatively rotatable to the shift spindle and rotates the master arm, a power storage collar that rotates integrally with the shift spindle, and a power storage spring provided between the gear shift arm and the power storage collar.
When a speed change signal is outputted during traveling and the shift spindle rotates in the motorcycle including the power storing mechanism like this, the gear shift arm receives a load in a direction to rotate the master arm via the power storage spring from the power storage collar. However, until the change clutch is disengaged by the clutch lever, a frictional force is applied to dog teeth side surfaces by a travel driving force in the shifter gear in the gear train of the transmission, so that the shift fork cannot move the shifter gear. That is, the shift drum cannot rotate. Consequently, even if the shift spindle rotates, the gear shift arm does not rotate the master arm, and a load is stored with rotation of the power storage spring. When the clutch lever disengages the change clutch after that, the frictional force on the dog teeth side surfaces is released by the travel driving force in the shifter gear in the gear train of the transmission, and the gear shift arm, the master arm and the shift drum are rotated at once by the load stored in the power storage spring and the rotation angle. Thereby, the time required for change of the gear train can be shortened.
In the AMT system, it is usual that the operation amount of the clutch operation member with which the change clutch is disengaged is known in advance, in order to be able to use the operation amount in various kinds of clutch control. Further, when it is desired to detect the clutch disengagement position with high precision with tolerance variation of each transmission taken into consideration, the clutch disengagement position is detected by various methods for each transmission, and the detected clutch disengagement position is stored in a nonvolatile memory (EEPROM, or the like) of the ECU in some cases, in the period until the transmission is used in traveling after completion of assembly of the transmission.